1. Field of the Invention
The invention relates in general to an antenna structure.
2. Description of the Related Art
Antenna used for receiving/receiving wireless signals is an essential element in a wireless communication device. The characteristics of antenna, such as radiation efficiency, directionality, frequency band, and impedance matching, have much to do with the efficiency of a wireless communication device. Currently, antenna can be divided into two categories: external antenna and internal antenna. Since the external antenna when colliding with an object may be easily bended or broken, more and more wireless communication devices adopt internal antenna. Since the internal antenna is embedded inside the wireless communication device, the appearance of the wireless communication device is made simpler and compacter. Furthermore, the internal antenna is much safer than the external antenna, which is disposed externally and may be easily bended or broken when colliding with an object, and has become a mainstream product of antenna for wireless communication devices. Therefore, how to provide an antenna structure with excellent efficiency has become a prominent task in the industries.